A cold front is moving south across Southern Colorado today, bringing a noticeable change for the plains while monsoon moisture continues to fuel showers and thunderstorms. The biggest temperature change will be east of the mountains, especially along and north of the Arkansas River. After Lamar reached 100 degrees on Labor Day, today will feel cooler as the front works through during the morning and afternoon.
Winds behind the front will become breezy, generally 10 to 20 mph, then turn more easterly at the surface during the afternoon. That easterly flow will help push low-level moisture up against the foothills and mountains. Combined with monsoon moisture already overhead, that sets the stage for a more active afternoon and evening than we saw Monday.
A few storms will develop in the monsoon plume over the mountains, but the stronger storms and better heavy-rain potential will be where the added low-level moisture is able to build in. Storms may begin developing after 1 p.m., with the Palmer Divide one area to watch along with the mountains, especially east of the Continental Divide.
The Pikes Peak region and northern Pueblo County could see storms around dinnertime and into the early evening. Storm coverage should also increase across the southeastern corner of Colorado through the evening, with activity gradually shifting eastward across the plains. Any storm will be capable of a quick downpour, and some could produce locally heavy rain.
Most storms will not be severe, but a few could put out wind gusts above 40 mph, particularly if storms cluster over the plains this evening. A brief window exists for a stronger updraft to produce hail near an inch in diameter, though hail of that size is not expected to be widespread. If a severe thunderstorm warning is issued, it may be for a storm that is close to severe limits rather than one producing widespread severe weather.
